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And Now, the Ecological Forecast

WASHINGTON, D.C.--The risk of rising seas and dried-up crops from global warming has gotten headlines for years. But lower profile environmental threats also loom on the horizon. On 20 February, ecologists at the annual meeting of the American Association for the Advancement of Science, which publishes ScienceNOW, predicted how these environmental insults will change the planet over the coming decades.

The researchers focused on four problems that are "potentially as significant 50 or 100 years down the road as global climate change," said ecologist David Tilman of the University of Minnesota, St. Paul. The list included:

Invasive species, such as gypsy moths, zebra mussels, and kudzu, sneak into the United States via ballast water or nursery shipments and rack up a $136 billion bill each year in destroyed trees, clogged intake pipes, and eradication efforts.

Organochlorine pesticides still used in developing countries ride air currents to the poles and accumulate in the fat of polar bears, seals, fish, and people--where they may interfere with the reproduction of wildlife and possibly lower the IQs of children.

A surfeit of nitrogen from fertilizers and fossil fuels spur established weeds to crowd out other plant species and contribute to massive marine algal blooms that suffocate fish.

And finally, the conversion of forest to farmland eats up habitat and contributes to global warming, erosion, and poor water quality.

These problems seem destined to get much worse, according to Tilman and three other ecologists. They modeled how land use and pollution may increase as economies grow and the world's population booms from 6 billion today to 8.9 billion people by 2050. The expected results: The amount of extra nitrogen and pesticides dumped into ecosystems is expected to triple by 2050. About a third of the natural forest, savanna, and grasslands today will be converted to farming--an area the size of Australia. And the United States can expect over two hundred new invasive species to take hold by the year 2020, upping the cost by $12 billion per year.

The ecologists urged people to control these threats to the environment as soon as possible. For example, they said, countries should protect natural habitats, crack down on stowaway pests, and pass laws that require removing nitrogen from farm manure and municipal waste.